Abstract

The infection with Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) frequentlycauses a broad range of long-lasting symptoms. This condition, termed long-COVID, influences everyday life of affected individuals in many ways and causes a high economic burden. There is urgent need to obtain better understanding of the risk factors that contribute to the development of long-COVID. Aim of this study was to investigate the long-COVID rate of supposedly healthy adults during different phases of the pandemic. Therefore, 71,670 blood donations were screened for SARS-CoV-2 total anti-N antibodies between 5^th June 2020 and 30^th November 2022. 351 individuals could be recruited for our study to monitor long-COVID symptoms and their duration. Despite immense worldwide efforts to stop virus dissemination, our data reveal a constantly rising SARS-CoV-2 anti-N seroprevalence rate in Salzburg, Austria, peaking at 84.9% in October 2022. In addition, our data demonstrate varying rates of long-COVID in the course of the pandemic. While long-COVID rates were about 20% for the time span between March 2020 and August 2021, long-COVID was reported by 12% for infections from September 2021 to August 2022. This could be attributed to different virus variants, but also to increasing vaccination rates. We further found that long-COVID symptoms decline over time: while 18% of our study participants described persisting symptoms 3 months after the seropositive blood donation, 14% reported persisting symptoms 9 months afterwards and 3% after 18 months. In conclusion, our data reveal that long-COVID symptoms may persist for more than a year after a SARS-CoV-2 infection and that long-COVID rates are varying in the course of the SARS-CoV-2 pandemic.

Keywords: SARS-CoV-2; COVID-19; Long-COVID; Seroprevalence; SARS-CoV-2 anti-N antibodies; Blood donation